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From:   Daniel Axtens <dja@axtens.net>
To:     Andrey Konovalov <andreyknvl@gmail.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Marco Elver <elver@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linuxppc-dev@lists.ozlabs.org, christophe.leroy@csgroup.eu,
        aneesh.kumar@linux.ibm.com, bsingharora@gmail.com
Subject: Re: [PATCH v15 2/4] kasan: allow architectures to provide an
 outline readiness check
In-Reply-To: <CA+fCnZdJ=HHn1Y=UDiYJ2NagNF9d-bJfjQa0jmiDaLiqneB_rA@mail.gmail.com>
References: <20210617093032.103097-1-dja@axtens.net>
 <20210617093032.103097-3-dja@axtens.net>
 <CA+fCnZdJ=HHn1Y=UDiYJ2NagNF9d-bJfjQa0jmiDaLiqneB_rA@mail.gmail.com>
Date:   Wed, 23 Jun 2021 19:25:12 +1000
Message-ID: <878s31hr0n.fsf@dja-thinkpad.axtens.net>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

>> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
>> index 10177cc26d06..0ad615f3801d 100644
>> --- a/mm/kasan/common.c
>> +++ b/mm/kasan/common.c
>> @@ -331,6 +331,10 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
>>         u8 tag;
>>         void *tagged_object;
>>
>> +       /* Bail if the arch isn't ready */
>
> This comment brings no value. The fact that we bail is clear from the
> following line. The comment should explain why we bail.
>
>> +       if (!kasan_arch_is_ready())
>> +               return false;

Fair enough, I've just dropped the comments as I don't think there's
really a lot of scope for the generic/core comment to explain why a
particular architecture might not be ready.

> Have you considered including these checks into the high-level
> wrappers in include/linux/kasan.h? Would that work?

I don't think those wrappers will catch the outline check functions
like __asan_load*, which also need guarding.

Kind regards,
Daniel